C. G. Cassapakis

Neutron spectra at 0° from p—p and p—d collisions at 647 and 800 MeV incident energies

Abstract The p—d spectra show sharp high-energy peaks (≈ 15 MeV FWHM) with integrated yields of 30 and 31 mb/sr, respectively and with lower-energy bumps associated with pion production. The p—p spectra reflect the influence of the Δ(1232) resonance.

Neutron spectra at 0° from (p, n) reactions on 9Be, 12C, and 27Al at 647 and 800 MeV

Abstract The measured cross sections show a narrow high-energy peak (20–30 MeV/ c FWHM ) and a broad bump at lower momenta associated with pion production. Comparison is made to an intranuclear cascade calculation.

Differential cross-section for n p elastic scattering in the angular region 50-degrees < Theta* < 180-degrees at 459-MeV

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Differential cross section for n − p elastic scattering in the angular range 51 ° θ * 180 ° at 647.5 MeV

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Measurement of (p,n) and (n,p) reactions on 6Li and 7Li at 800 MeV☆

Abstract The measured 7 Li(p,n), and 6 Li(n,p) cross sections at 0° show a high-energy peak (≈25 MeV/ c FWHM) which we attribute primarily to nuclear charge exchange leading to final states in 7 Be, 6 Be, and 6 He, respectively. By contrast, the 7 Li(n,p) cross section at O° shows a broad weak high-energy peak believed due mostly to break-up processes. At 16°, the 6,7 Li(n,p) cross sections are dominated by quasi-elastic scattering.

Neutron spectra at 0° from proton-proton collisions between 647 and 805 MeV

Momentum spectra of neutrons at 0degree from the process pp ..-->.. np..pi../sup +/ have been measured at 647, 771, and 805 MeV. Absolute cross sections d/sup 2/sigma/d..cap omega..dp and dsigma/d..cap omega..* are given for all three energies. A phenomenological calculation using only S- and P-wave ..pi..N phase shifts and an NN final-state interaction appears to account for the shapes and magnitudes of the spectra quite well. Comparison with the process np ..-->.. pX indicates a non-negligible contribution from nonresonant amplitudes. (AIP)

Differential Cross-Section for N-P Elastic-Scattering in the Angular Range 60-Degrees Less-than Theta-Star Less-than 180-Degrees at 801.9 Mev

The differential cross section for n-p elastic scattering at 801.9 MeV has been measured with high statistical precision and good relative accuracy over the angular range 60/sup 0/..d..pi../sup 0/ reaction and is good to 7%. A nearly monoenergetic neutron beam, produced by proton bombardment of a liquid-deuterium target, was directed through a liquid-hydrogen target. The angle, velocity, and momentum of charged particles ejected from the target were measured in a magnetic spectrometer equipped with multiwire proportional chambers and timing scintillators. The results are in good agreement with earlier Saclay and LAMPF data and include an angular region not covered before. The pole-extrapolation method of Chew was used to extract a value f/sup 2/ = 0.075 +- 0.005 for the pion-nucleon coupling constant which is in agreement with accepted values, thus providing evidence for the accuracy of the shape and normalization of the angular distribution.

Extreme back angle n/sup 2/H elastic scattering at 794 MeV

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139/sub D/ to 179/sub D/. The angular distribution is fitted very well both by an empirical function ..cap alpha..e/sup ..beta../(u-u180D)/sup / and by a calculation that uses the one parameter Craigie-Wilkin triangle diagram technique.

Extreme back anglenH2elastic scattering at 794 MeV

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139/sub D/ to 179/sub D/. The angular distribution is fitted very well both by an empirical function ..cap alpha..e/sup ..beta../(u-u180D)/sup / and by a calculation that uses the one parameter Craigie-Wilkin triangle diagram technique.

Neutron spectra at 0degree from proton-proton collisions between 647 and 805 MeV. [Absolute cross sections, sand P waves, phase shift, NN final-state interaction]

Momentum spectra of neutrons at 0degree from the process pp ..-->.. np..pi../sup +/ have been measured at 647, 771, and 805 MeV. Absolute cross sections d/sup 2/sigma/d..cap omega..dp and dsigma/d..cap omega..* are given for all three energies. A phenomenological calculation using only S- and P-wave ..pi..N phase shifts and an NN final-state interaction appears to account for the shapes and magnitudes of the spectra quite well. Comparison with the process np ..-->.. pX indicates a non-negligible contribution from nonresonant amplitudes. (AIP)